在bash脚本中从grep打印输出会产生损坏的字符串 [英] Printing output from grep in bash script yields broken string

问题描述

我有以下简单的bash脚本，将命令的输出存储在变量中并打印出来:

I have the following simple bash script that stores the output of a command in a variable and prints it:

size=$(curl -sI "http://speedtest.reliableservers.com/1GBtest.bin" | grep -i "length")

echo "--> ${size} <--"

在终端中运行命令时，得到以下输出:

When running the command in the terminal, I get the following output:

Content-Length: 1073471824

但是当我运行调用命令的bash脚本时，会得到以下输出:

But when I run this bash script that invokes the command, I get the following output:

 <--Content-Length: 1073741824

这是怎么回事?

推荐答案

问题是HTTP响应标头以CRLF或\r\n结尾. $(..)确实去除了\n，但没有去除\r，因此输出将是

The problem is that the HTTP response header ends with CRLF or \r\n. The $(..) does strip the \n but not the \r, so that the output will be

--> 1073741824\r <--

其中\r回车将光标设置到行的开头，并用<--覆盖-->.

where the \r carriage return sets the cursor to the start of the line, overwriting --> with <--.

您可以使用sed剥离\r:

size=$(curl -sI "http://speedtest.reliableservers.com/1GBtest.bin" | grep -i "length" \
     | sed -e 's/\r//' )

echo "--> ${size} <--"

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